Ultrasonic medical treatment device for bipolar RF cauterization and related method

ABSTRACT

An ultrasonic medical treatment device has a casing, an elongate probe, a transducer assembly, a sheath and a plurality of electrode members. The probe is mounted to and extends from the casing and has an axis and a free end serving as an operative tip. The transducer assembly is mounted to the casing and is operatively connected to the probe for generating vibrations of at least one ultrasonic frequency in the probe. The sheath surrounds the probe. The electrode members are connectable to an RF voltage source and are mounted at least indirectly to the casing so as to permit relative motion between the electrode members and the probe.

FIELD OF THE INVENTION

[0001] This invention relates to a medical device and more specificallyto an ultrasonic tissue ablation instrument. Even more specifically,this invention relates to an ultrasonic medical treatment device withelectrocautery. This invention also relates to an associated medicaltreatment method.

BACKGROUND OF THE INVENTION

[0002] Many diseases of the brain and spine require surgery to providethe patient with relief. These could include cancer, non-malignantlesions and trauma induced by accidents or physical attack. As aprocedure, neurosurgery has been practiced for several millennia.Archeologists have discovered evidence of sophisticated cranial surgeryin relics and skulls dating back to Roman times. The tools found havebeen shown to be remarkably similar to today's designs. Of course, modemscience has substantially improved upon the techniques and resultsobtained in those days.

[0003] One of the biggest steps forward occurred approximately 30 yearsago with the invention and marketing of the ultrasonic surgicalaspirator. This device utilizes a hollow probe or tool that vibrates atfrequencies at or above 20 kc with tip amplitudes of up to 300 microns.When the vibrating tip is placed against viable or diseased tissue, themoving tip ablates the cells and causes them to fragment or otherwiseemulsify in the irrigation fluid that is being added simultaneously. Theemulsified fluid is then aspirated through the hollow probe anddeposited in a canister for histological examination or disposal.

[0004] The advantage of excising tissue with this device is that thesurgeon can remove the lesion in layers almost 5 cells thick. By slowlyremoving the tumor from the top down, he can clearly see when he isreaching healthy tissue allowing him to stop before substantialcollateral damage occurs. This is extremely desirable in brain and spinesurgery, where tissue does not regenerate. Gastrointestinal surgeonshave used the device as well for lesions of the liver and spleen, forthe same reasons.

[0005] The required specifications, designs and engineering elements ofsuch ultrasonic aspirators have become well known to the art in theintervening time. Although the technology is mature, severalimprovements can be made to enhance the ease of use and applicability toa wider range of procedures.

[0006] One side effect of any surgery is bleeding when the veins,arteries or capillaries are severed. Ultrasonic surgery is more sparingof blood vessels than knives because the collagen content of the vesselsis more resistant to ultrasonic emulsion. However, the capillaries andsmall vessels will be compromised upon exposure to high amplitudeultrasonic tools. When these vessels are severed or punctured bleedingwill of course occur. The surgeon will then be forced to pause theprocedure, remove the ultrasonic tool from the site and generally reachfor a cauterizing device of some type to close off the bleeder. Oncecoagulation has been achieved, then the surgeon can grab the ultrasonictool, reposition it in the wound site and continue the removal oftissue. This situation repeats itself often in the course of theoperation, lengthening the time of the procedure and coincidently therisk to the patient. It is therefore desired to find a way to cauterizetissue with the ultrasonic tool in place so the surgeon can stopbleeding with minimal downtime caused by switching tools and positions.

[0007] Several improvements to the basic design of the ultrasonicaspirator have been disclosed over the years which allows some degree ofcauterization subsequent to or simultaneously with ultrasonic ablation.Most center on the application of RF cautery currents to the tool orprobe itself. This has the effect of turning the ultrasonic tool into amonopolar RF cauterizer.

[0008] In a non-ultrasonic RF cauterizer, the tip of the tool isenergized with a voltage sometimes exceeding 3000 volts RMS. Thefrequency of the voltage is very high, in order to prevent cardiacarrest in the patient. These frequencies are generally greater than500,000 hertz. In monopolar RF, the tool is one pole of the electricalcircuit. The second pole is generally a large piece of metal foil whichthe patient lays on during the procedure. The bare skin touching thefoil makes an effective electrical contact. As the tool touches thetissue and the RF voltage is energized, a complete circuit path iscreated. The currents are very high, reaching 5 amps in some cases. Atthese currents, significant joule heating occurs in the tissue, raisingthe temperature higher than the burning temperature of 42° C. Continuedoperation dries the tissue by evaporating the water content.Cauterization then occurs. Since the back plate is very large inrelation to the tool tip, the current “fans out” as it leaves the tooltip and thereby lowers the current density in the tissue to a pointwhere the temperature rise in the tissue is reduced to that belowburning. This minimizes collateral burning and tissue damage.

[0009] However, as large as the plate is, some collateral damage occursaway from the bleeder site. This collateral damage cannot be controlledreliably by the physician and is of great concern when operating on thebrain. If the damage is two widespread, mental capacity or memory may beaffected negatively. In addition, electrical current is forced to flowthrough viable tissue to the ground plate. Again, neurological damagemay occur in some organs that are susceptible to damage due to thiscurrent, such as the brain, heart and nerve bundles. Other organs, suchas the liver or spleen, are less susceptible to current effects.

[0010] Researchers have found a way to minimize or eliminate thiscurrent path by designing a tool that includes two electrical poles orcontacts. This is called bipolar RF cauterization. Here the currentflows between the two poles through the intervening tissue. No currentpath to the back is allowed. Therefore, the tissue that is damaged isonly that caught between the two contacts, which can be very small.

[0011] Designers have found a way to add monopolar cautery to ultrasonicdevices by connecting one electrical contact to the vibrating tip of theultrasonic device. Several patents have disclosed concepts andtechniques for this, such as U.S. Pat. No. 4,931,047 to Broadwin, et al.Here, the tip of the ultrasonic tool is the single pole that touches thetissue. The surgeon will generally stop ultrasonic vibration and turn onthe cautery voltage. Current leaves the tip of the probe and goesthrough the body to the back plate. This has been shown to be effectivein eliminating the need for switching tools to stop bleeding, savingtime and effort on the doctor's part. However, all of the detriments ofmonopolar cautery still exist. Neurosurgeons are especially reticent toallow significant current to flow through brain or spinal cord tissuefor fear of inducing neurological damage. In addition, the piezoelectriccrystals of the ultrasonic transducer stack must be isolated from thecautery voltage or damage to the transducer or electronics will occur.

OBJECTS OF THE INVENTION

[0012] It is an object of the present invention to provide an ultrasonictreatment device or instrument having electrocautery capability.

[0013] Another object of the present invention is to provide such adevice that eliminates the above-described deficiencies in conventionalsystems.

[0014] A further object of the present invention to provide such adevice or instrument which is easy to use and which provides reliablecautery effects while minimizing patient risk during an ultrasonicaspiration procedure.

[0015] Yet another object of the present invention is to provide such adevice or instruments with a capability of grasping and clamping tissueor vessels prior to and concurrent with electrocautery.

[0016] A related object of the present invention is to provide anassociated method which combines ultrasonic ablation with electrocauteryin a manner that is easy to use.

SUMMARY OF THE INVENTION

[0017] An ultrasonic medical treatment device pursuant to the presentinvention comprises a casing, an elongate probe, a transducer assembly,a sheath and a plurality of electrode members. The casing is generallyin the form of a handpiece which facilitates manipulation by a surgeon.The probe is mounted to and extends from the casing and has an axis anda free end serving as an operative tip. The transducer assembly ismounted to the casing and is operatively connected to the probe forgenerating vibrations of at least one ultrasonic frequency in the probe.As is well known, the ultrasonic vibration frequency is a resonantfrequency of the probe, whereby standing waves are produced in theprobe. The sheath surrounds the probe. The electrode members areconnectable to an RF voltage source and are mounted at least indirectlyto the casing so as to permit relative motion between the electrodemembers and the probe.

[0018] In a preferred embodiment of the invention, the electrode membersare attached to the sheath, which is movably mounted to the casing. Itis also preferred that the electrode members are fixed to andsubstantially embedded in the sheath. The electrode members have exposedportions disposed proximately to the operative tip of the probe forforming electrically conductive contact with organic tissues at asurgical site in a patient.

[0019] More particularly, the sheath is movably mounted to the casingfor reciprocatable motion along the axis of the probe, whereby the tipof the probe may be alternately covered and exposed. Thus, during anultrasonic use of the instrument, the sheath is retracted to expose theoperative tip of the probe, which is energized by a predeterminedultrasonic vibration produced by the transducer assembly. Should a bloodvessel become severed by ultrasonic ablation, the action of thetransducer assembly is interrupted and the sheath slid forward, in adistal direction, to cover the tip of the probe and to facilitatecontact between the exposed portions of the electrode members and theregion about the severed blood vessel. The electrode members are thenconnected to a radio-frequency current source to generate a current flowbetween the exposed portions of the electrode members.

[0020] The electrode members may be exactly two in number. In that case,the exposed portions of the electrode members are preferably disposed atan angle of less than 90° from one another. However, in someapplications it may be preferred to have the exposed portions of theelectrode members angularly spaced by a greater angle, up to 180°.

[0021] In another embodiment of the invention, there are two or morepairs of electrode members, with the members of each pair being disposedadjacent to one another along the circumference of the sheath. In thisembodiment, a manually operable switching circuit may be operativelyconnected between the power source and the electrode members fordetermining which pair of electrode members is to be energized. Theoperating surgeon selects that pair of electrode members which is mostclosely located to a bleeding site.

[0022] Pursuant to another feature of the present invention, theelectrode members are movable in parallel to the axis of the probe.

[0023] A medical surgical method in accordance with the presentinvention utilizes an ultrasonic medical treatment device having acasing and an elongate probe mounted to and extending from the casing,the probe having an axis and a free end serving as an operative tip, atransducer assembly mounted to the casing being operatively connected tothe probe, a plurality of electrode members being mounted at leastindirectly to the casing. The method comprises inserting a distal endportion of the probe into a patient, thereafter energizing thetransducer assembly to generate a standing wave of an ultrasonicfrequency in the probe, ablating tissues of the patient at the operativetip of the probe during the generating of said standing wave, connectingthe electrode members to an RF voltage source, and cauterizing tissuesin the patient owing to the conduction of current between exposedportions of the electrode members.

[0024] Pursuant to another feature of the present invention, theelectrode members are moved relative to the probe, thereby placing theexposed portions of the electrode members in a predeterminable locationrelative to the operative tip. Where the electrode members are connectedto a sheath, the moving of the electrode members may be accomplished byshifting the sheath relative to the probe.

[0025] In a further embodiment, the two electrodes may be spaced 180degrees apart and be hinged nearer the proximal end of the sheath. Twoprotuberances may be provided, extending outside the outer sheathassembly, which contact the rigid metal electrodes. By sliding thesheath forward, the distal ends of the electrodes are exposed. Theseelectrodes may be manipulated by the surgeon to allow tissue to fill thegap between said electrodes. By squeezing the protuberances, the surgeonmay apply a pinching force on the tissue to help close severed vesselswhile applying electrocautery current.

[0026] It is to be noted that the electrodes may be used to ablatetissues of the patient in addition to cauterizing the ablated tissues.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1A is a partial longitudinal cross-section view of a nultrasonic tissue ablation instrument with electrocautery, in accordancewith the prior art.

[0028]FIG. 1B is a side elevational view of a transducer assembly usedin the prior-art surgical instrument of FIG. 1A.

[0029]FIG. 2A is a schematic side-elevational view of a human subject,showing an electrocautery plate and, in phantom lines, a possiblecurrent path where the instrument of FIG. 1A is used in neurosurgery.

[0030]FIG. 2B is another schematic side-elevational view of a humansubject, showing an electrocautery plate and, in phantom lines, anotherpossible current path where the instrument of FIG. 1A is used inneurosurgery.

[0031]FIG. 3A is a partial longitudinal cross-sectional view of a distalend portion of an ultrasonic tissue ablation instrument withelectrocautery, in accordance with the present invention.

[0032]FIG. 3B is an end elevational view of the instrument of FIG. 3A,taken from the right said in FIG. 3A.

[0033]FIG. 4A is a partial longitudinal cross-sectional view, takenalong line IVA-IVA in FIG. 4B, of a distal end portion of anotherultrasonic tissue ablation instrument with electrocautery, in accordancewith the present invention.

[0034]FIG. 4B is an end elevational view of the instrument of FIG. 4A,taken from the right side in FIG. 4A.

[0035]FIG. 5A is a partial longitudinal cross-sectional view of thetissue ablation instrument of FIGS. 3A and 3B, depicting one structurefor shifting a sheath and electrodes relative to an ultrasonic probe andshowing the sheath in a retracted position to expose a free end of theprobe.

[0036]FIG. 5B is a partial longitudinal cross-sectional view similar toFIG. 5A, showing the sheath in an extended position to cover a free endof the probe and place operative ends of the electrodes in contact withorganic tissues at a surgical site.

[0037]FIG. 6A is a partial longitudinal cross-sectional view of thetissue ablation instrument of FIGS. 3A and 3B, depicting anotherstructure for shifting the sheath and electrodes relative to the probeand showing the sheath in a retracted position to expose the free end ofthe probe.

[0038]FIG. 6B is a partial longitudinal cross-sectional view similar toFIG. 6A, showing the sheath in an extended position to cover a free endof the probe and place operative ends of the electrodes in contact withorganic tissues at a surgical site.

[0039]FIG. 7A is a perspective view of a distal end portion of yetanother ultrasonic tissue ablation instrument with electrocautery, inaccordance with the present invention, showing a pair of electrodeshingedly mounted to a movable sheath disposed in a retracted position toexpose an operating tip of an ultrasonic ablation probe.

[0040]FIG. 7B is a perspective view of the instrument of FIG. 7A,depicting the movable sheath slid forward to cover the operating tip ofthe ultrasonic ablation probe and to expose the distal ends of theelectrodes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0041] Disclosed herein are various hardware configurations that willallow bipolar RF cautery to be used on organic tissues at a surgicalsite simultaneously with or immediately after ultrasonic ablation oftissue. The electrical connections are isolated from the ultrasonic toolthereby allowing the piezoelectric crystals to be floating with respectto this potential.

[0042] In the prior art, as shown in FIG. 1A, an ultrasonic probe 12 isconnected one pole of an RF cauterizer (not shown) by a wire 14.Alternatively, an electrode member, conductive O rings or other methodsknown to the art (none shown) may be used. In the embodiment of FIGS. 1Aand 1B, a front driver 16 of the transducer is also rendered live, whichnecessitates that the metal parts be insulated from the grip or handle17 of the instrument. If the transducer assembly 18 is of theelectrostrictive type with piezoelectric crystals 20, the crystals mustbe electrically isolated from the front driver 16 by methods known tothe art such as using ceramic washers 22 and 24 as insulation in thecrystal stack (FIG. 1B). A disadvantage of using isolators is that theygenerally reduce the electromechanical coupling efficiency, therebyleading to transducer heating and higher power requirements for a givenoutput amplitude.

[0043] The other pole of the RF cauterizer is attached to a back plate26 that contacts the patient's bare skin, as shown in FIGS. 2A and 2B.Then the entire body becomes part of the electrical connection. Possiblecurrent paths 28 and 30 are shown in FIGS. 2A and 2B.

[0044] As depicted in FIGS. 3A and 3B, both electrical poles orelectrode members 32 and 34 of an electrocautery system are attached toand, more specifically, embedded in, a flexible silicone sheath 38 thatsurrounds an elongate ultrasonic probe 40. Ultrasonic aspirators requirethe addition of a sterile solution of saline into the wound site toirrigate the area and improve ablation. Sheath 38 serves to define, withprobe 40, an annular conduit 42 for this saline solution.

[0045] In the embodiment of FIGS. 3A and 3B, electrode members 32 and 34in the form of wires are molded into the silicone sheath or flue 38. Thedistal ends or tips 44 and 46 of the electrodes members 32 and 34protrude from the distal end of sheath 38, forming two electrodes.

[0046] By utilizing the sheath 38 as a holder for the two electrodemembers 32 and 34 of the bipolar device, the electrical connections donot touch the tool itself. The close proximity of electrode members 32and 34, and particularly exposed tips 44 and 46 thereof, allows a veryshort circuit path (FIG. 3B) for the cauterizing current. To use of thecauterizing capability of the instrument of FIGS. 3A and 3B, theinstrument is rotated about a longitudinal axis 48 by the surgeon inorder to approximate the exposed tips 44 and 46 of the electrode members32 and 34 to bleeding tissues at a surgical site inside a patient.

[0047]FIGS. 4A and 4B depict an alternative configuration of electrodes50-53 in a flexible silicone sheath 54 surrounding an ultrasonic probe56. Electrodes 50-53 are circumferentially equispaced about the sheath54. Electrodes 50-53 are ring segments (i.e., arcuate about an axis ofsheath 54) molded into the end of sheath 54. Electrodes 50-53 have gapsbetween them for insulation purposes. Electrodes 50-53 are connected toelectrode wires 58 and 60 that are embedded in sheath 54. The wires 58and 60 are each connected to two electrodes or segments 50-53 disposed180° apart. During an electrocautery operation, current is conductedbetween each pair of adjacent electrodes, thus producing four zones ofpossible tissue cauterization corresponding to the four gaps betweenelectrodes 50-53.

[0048] In the embodiment of FIGS. 4A and 4B, a finer control ofcauterization location may be achieved by having electrodes 50-53connected to respective wires. Wires 58 and 60 are thus each connectedto a single electrode 50, 51, 52, or 53. In this embodiment, a singlepair of adjacent electrodes 50-53 is selected for energization at anyone time. Generally, a pair is selected that is considered closest tobleeding tissues at a surgical site in a patient. When the RF current isenergized, the segments will allow current to flow between the gaps ofthe segmented ring around the periphery of the sheath end. It can beenvisioned by those schooled in the art that logic circuitry may beprovided to energize only two segments of a multi-segmented ring toallow current to pass through only one or two gaps and not all of thegaps provided.

[0049] The configurations of FIGS. 3A, 3B and 4A, 4B have been developedto provide physicians with designs that can be used without losingdexterity or visibility of the operation site. The electrode memberconfigurations of FIGS. 3A, 3B and 4A, 4B allow for bipolarcauterization without energizing the tool tip itself.

[0050] In order to allow the surgeon the best visualization of theoperative field, mechanisms have been developed for use with the devicesof FIGS. 3A, 3B and 4A, 4B that provide for a longitudinal translationof sheaths 38 and 54 alternately in a distal direction and a proximaldirection. While the ultrasound is active, sheath 38 or 54 is slid backto expose the distal end or operative tip 78 or 79 of the probe 40 or56. When RF cautery is needed, the surgeon uses one finger (e.g., athumb) to slide the sheath 38 or 54 forward to place the electrodes 44,46 or 50-53 in contact with the tissue. FIGS. 5A and 5B show a firstembodiment of this mechanism, constructed of molded or machined plastic,while FIGS. 6A and 6B show an alternative embodiment of the slidemechanism. Although FIGS. 5A, 5B, 6A, and 6B depict the electrodeconfiguration of FIGS. 3A and 3B, it is to be understood that theelectrode configuration of 4A and 4B could be used instead.

[0051] As illustrated in FIGS. 5A and 5B, probe 40 is connected at aproximal end to a piezoelectric transducer assembly 62, while sheath 38is affixed to the distal end of a polymeric inner tubular member 64telescopingly cooperating with an outer tubular member or casing 66.Casing 66 extends in a rearward or proximal direction to form a handgripor handpiece for a surgeon or other user of theultrasonic/electrocautery instrument. Annular conduit 42 communicates ata proximal end with an annular passageway 68 formed by probe 40 andinner tubular member 64. Passageway 68 communicates with a saline source(not shown) via a nippled coupling 70 and an aperture 72 formed in innertubular member 64. Inner tubular member 64 is provided with a projection76 serving as a manually operable control knob for sliding sheath 38 andelectrode members 32 and 34 (a) in the distal direction prior to theenergization of electrode members 32 and 34 and electrode tips 44 and 46in an electrocautery operation and (b) in a proximal direction prior toan ultrasonic ablation procedure in which probe 40 is vibrated bytransducer assembly 62. During an ultrasonic ablation procedure, a freeend or operative tip 78 of probe 40 vibrates with a maximizeddisplacement (at an antinode of the standing wave generated in probe40).

[0052] The telescoping cooperation of inner tubular member 64 and casing66 enables a reciprocating motion of sheath 38 and electrode members 32and 34 along the axis 48 of probe 40, whereby the operative tip 78 ofthe probe may be alternately covered and exposed. Thus, during anultrasonic use of the instrument, sheath 38 is retracted to expose theoperative tip 78 of the probe 40, which is energized by a predeterminedultrasonic vibration produced by the transducer assembly 62. Should ablood vessel become severed by ultrasonic ablation, the action oftransducer assembly 62 is interrupted and sheath 38 is slid forward, ina distal direction, to cover tip 78 of probe 40 and to facilitatecontact between the exposed portions of the electrode members, i.e.electrode tips 44 and 46, and the region about the severed blood vessel.Electrode members 32 and 34 are then connected to a radio-frequencycurrent source (not illustrated) to generate a current flow between theexposed portions of the electrode members 32 and 34.

[0053] As depicted in FIGS. 6A and 6B, probe 40 is connected at aproximal end to a piezoelectric transducer assembly, while sheath 38 isaffixed to the distal end of a polymeric tubular member 82 attached viaan annular bellows 84 to a handpiece casing 86. Annular conduit 42communicates at a proximal end with an annular passageway 88 formed byprobe 40 and tubular member 82. Passageway 88 communicates with a salinesource (not shown) via a nippled coupling 90 and an aperture 92 formedin tubular member 82. Tubular member 82 is provided with a projection 96serving as a manually operable control knob for sliding sheath 38 andelectrode members 32 and 34 (a) in the distal direction prior to theenergization of electrode members 32 and 34 and electrode tips 44 and 46in an electrocautery operation and (b) in a proximal direction prior toan ultrasonic ablation procedure in which probe 40 is vibrated bytransducer assembly 62.

[0054] The distensible connection of tubular member 82 and casing 86 viabellows 84 enables a reciprocating motion of sheath 38 and electrodemembers 32 and 34 along the axis 48 of probe 40, whereby the operativetip 78 of the probe may be alternately covered and exposed, as discussedhereinabove with reference to FIGS. 5A and 5B. Bellows 84 provides themechanism with a seal against the transducer housing (tubular member 82)to prevent fluid leaks.

[0055] As illustrated in FIGS. 7A and 7B, two electrodes 102 and 104 maybe spaced 180° apart and hinged (e.g., via a flexible joint) nearer theproximal end of a sheath 106. Sheath 106 is provided with two pairs oflongitudinal parallel slots 108 defining respective fingers 110 and 112in which electrode wires (not separately illustrated) are embedded. Twoactuators in the form of protuberances 114 and 116 are provided,extending through respective opposed apertures 118 (only one shown) in acasing 120. Protuberances 114 and 116 are connected to fingers 110 and112, respectively, near the proximal ends thereof. Pushing one or bothprotuberances 114 and 116 in a longitudinal direction, along an axis(not indicated) of the instrument, slides sheath 106 either forward tocover an operating tip of an ultrasonic probe 122, as depicted in FIG.7B, or rearwards to expose the probe tip, as depicted in FIG. 7A. Asurgeon may also manipulate electrodes 102 and 104 to insert targetorganic tissues between the electrodes prior to an electrocauteryoperation. By squeezing protuberances 114 and 116 towards one another,the surgeon may apply a pinching force on the tissue to help closesevered vessels while applying electrocautery current via electrodes 102and 104. In an application of compressive pressure to protuberances 114and 114, electrodes 102 and 104 function as tweezers, exerting asqueezing force on trapped tissue, thereby enhancing the vessel sealingeffect of the electrodes and minimizing collateral damage.

[0056] Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. It is to be noted, for instance, that theelectrocatuery portion of a combined ultrasonic ablation andelectrocautery tool as disclosed herein may be used for ablation, aswell as cautery. It is to be noted, in addition, that the electrodes maybe attached to the probe casing or frame by means other than the sheath.Accordingly, it is to be understood that the drawings and descriptionsherein are proffered by way of example to facilitate comprehension ofthe invention and should not be construed to limit the scope thereof.

What is claimed is:
 1. An ultrasonic medical treatment devicecomprising: a casing; an elongate probe mounted to and extending fromsaid casing, said probe having an axis and a free end serving as anoperative tip; a transducer assembly mounted to said casing andoperatively connected to said probe for generating vibrations of atleast one ultrasonic frequency in said probe; a sheath surrounding saidprobe; and a plurality of electrode members attached to said sheath,said electrode members being connectable to an RF voltage source.
 2. Themedical treatment device defined in claim 1 wherein said sheath ismovably mounted to said casing for reciprocatable motion along said axisof said probe, whereby said tip of said probe may be alternately coveredand exposed.
 3. The medical treatment device defined in claim 2 whereinsaid electrode members are fixed to said sheath.
 4. The medicaltreatment device defined in claim 3 wherein said electrode members aresubstantially embedded in said sheath and have exposed tips proximate tosaid operative tip of said probe.
 5. The medical treatment devicedefined in claim 4 wherein said electrode members are exactly two innumber.
 6. The medical treatment device defined in claim 4 wherein saidelectrode members include a plurality of pairs of electrode members. 7.The medical treatment device defined in claim 2 wherein at least one ofsaid electrode members is hingedly secured to said sheath, furthercomprising at least one actuator operatively connected to said one ofsaid electrode members for pivoting said one of said electrode memberstowards the other of said electrode members.
 8. The medical treatmentdevice defined in claim 7 wherein said sheath is formed with a pluralityof pairs of parallel slots defining respective hinged fingers, saidelectrode members being mounted to respective ones of said hingedfingers.
 9. The medical treatment device defined in claim 8 wherein saidelectrode members are at least partially embedded in said fingers. 10.The medical treatment device defined in claim 7 wherein said actuator isa protuberance manually engageable to slide said sheath alternately in aproximal and a distal direction.
 11. The medical treatment devicedefined in claim 1 wherein said electrode members are mounted to saidsheath so as to be movable relative to said probe.
 12. The medicaltreatment device defined in claim 11 wherein said electrode members aremovable in parallel to said axis.
 13. The medical treatment devicedefined in claim 1 wherein said electrode members are fixed to saidsheath.
 14. The medical treatment device defined in claim 1 wherein saidelectrode members are substantially embedded in said sheath and haveexposed tips proximate to said operative tip of said probe.
 15. Anultrasonic medical treatment device comprising: a casing; an elongateprobe mounted to and extending from said casing, said probe having anaxis and a free end serving as an operative tip; a transducer assemblymounted to said casing and operatively connected to said probe forgenerating vibrations of at least one ultrasonic frequency in saidprobe; a sheath surrounding said probe; and a plurality of electrodemembers connectable to an RF voltage source, said electrode membersbeing mounted at least indirectly to said casing so as to permitrelative motion between said electrode members and said probe.
 16. Themedical treatment device defined in claim 15, further comprising meansmounting said electrode members to said casing so as to permit relativemotion between said electrode members and said probe.
 17. The medicaltreatment device defined in claim 16 wherein said means mounting saidelectrode members to said casing includes said sheath, said sheath beingmovably mounted to said casing for reciprocatable motion along said axisof said probe, whereby said tip of said probe may be alternately coveredand exposed.
 18. The medical treatment device defined in claim 17wherein said electrode members are mounted to said sheath so as topermit a transverse motion of a distal end of at least one saidelectrode members relative to said probe, thereby permitting anadjustment in the distance between the distal ends of said electrodemembers.
 19. The medical treatment device defined in claim 18 wherein atleast one of said electrode members is hingedly secured to said sheath,further comprising at least one actuator operatively connected to saidone of said electrode members for pivoting said one of said electrodemembers towards the other of said electrode members.
 20. The medicaltreatment device defined in claim 19 wherein said sheath is formed witha plurality of pairs of parallel slots defining respective hingedfingers, said electrode members being mounted to respective ones of saidhinged fingers.
 21. The medical treatment device defined in claim 20wherein said electrode members are at least partially embedded in saidfingers.
 22. The medical treatment device defined in claim 19 whereinsaid actuator is a protuberance manually engageable to slide said sheathalternately in a proximal and a distal direction.
 23. The medicaltreatment device defined in claim 17 wherein said electrode members aresubstantially embedded in said sheath and have exposed tips proximate tosaid operative tip of said probe.
 24. A method for conducting a medicalsurgical procedure, comprising: providing an ultrasonic medicaltreatment device having a casing and an elongate probe mounted to andextending from said casing, said probe having an axis and a free endserving as an operative tip, a transducer assembly mounted to saidcasing being operatively connected to said probe, a plurality ofelectrode members being mounted at least indirectly to said casing;inserting a distal end portion of said probe into a patient; thereafterenergizing said transducer assembly to generate a standing wave in saidprobe, said standing wave having a wavelength corresponding to anultrasonic frequency; during the energizing of said transducer assembly,ablating tissues of the patient at said operative tip of said probe;connecting said electrode members to an RF voltage source; andthereafter cauterizing tissues in the patient owing to the conduction ofcurrent between exposed portions of said electrode members.
 25. Themethod defined in claim 24, further comprising moving said electrodemembers relative to said probe, thereby placing the exposed portions ofsaid electrode members in a predeterminable location relative to saidoperative tip.
 26. The method defined in claim 25 wherein said electrodemembers are attached to said sheath, the moving of said electrodemembers including moving said sheath relative to said probe.
 27. Themethod defined in claim 26 wherein the moving of said electrode membersincludes translating said sheath in parallel to said probe.
 28. Themethod defined in claim 26 wherein the moving of said electrode membersincludes moving at least one of said electrode members in a transversediection relative to said probe and relative to another of saidelectrode members, thereby chaning a distance between exposed portionsof said one of said electrode members and said another of said electrodemembers
 29. The method defined in claim 24, further comprising usingsaid electrode members to ablate tissues of the patient.